The present invention relates to an insulator for insulating the core of an electric rotating machine from coils wound around the core and a method for manufacturing the insulator. The present invention also pertains to a stator for an electric rotating machine.
A typical stator of an electric rotating machine such as a brushless motor, includes a core, which has teeth, and coils each wound around one of the teeth. The core has an annular portion and the teeth extend from the annular portion radially toward the center of the annular portion. Each coil is wound around one of the teeth with an insulator arranged in between.
As an example of such a core, a core that is formed by coupling several core segments in annular form has been proposed. Each core segment includes a tooth and is formed by laminating thin plate-like piece members. A coil is wound around the tooth of each core segment before coupling the core segments with one another. Therefore, a coil is easily wound around a tooth without interfering with the adjacent teeth.
In a stator disclosed in Japanese Laid-Open Patent Publication No. 7-222383, each core segment is formed by alternately laminating first piece members and second piece members. Each core segment has an arcuate portion, which forms part of the annular portion of the core. At the circumferential ends of the arcuate portion of each core segment, the ends of each first piece member and the ends of each second piece member are displaced in the circumferential direction. Therefore, the circumferential ends of the arcuate portion of each core segment have a shape in which recesses and projections are alternately arranged. Each of the circumferential ends of each core segment is coupled to the corresponding circumferential end of the adjacent core segment with a pin so that the annular core is obtained when all the core segments are coupled to one another. In a state where the projections of one of the adjacent core segments are fitted to the recesses of the other core segment, that is, in a state where the projections of the adjacent core segments overlap one another in the axial direction, a pin is inserted through the overlapped projections. In such a core, the adjacent core segments are reliably coupled to each other without forming a space in between. This reduces magnetic resistance at the annular portion and forms a reliable magnetic circuit. Also, since the projections overlap one another in the axial direction, the coupled core segments are prevented from being displaced in the axial direction.
When manufacturing the stator, a coil is wound around each separate core segment before coupling the core segments with one another with the pins. After winding each coil to the corresponding core segment, the core segments are coupled to one another with the pins. This makes the manufacturing process for the stator difficult and complicates handling of the core segments. The pins used for coupling the core segments increase the number of components.
Japanese Laid-Open Patent Publication No. 2002-247788 discloses an insulator attached to each of the core segments. The insulator corresponds to one core segment and is separate from an insulator attached to another core segment. Before winding a coil about each core segment, the insulator is attached to each core segment. This makes the manufacturing process for the stator difficult and increases the manufacturing time and the manufacturing cost.